Hey guys. I'll try to make it simple. I write questions. You answer. Works for you?

Q1. During the Sytris period, was Mars terraformed? If yes, then why did the CW settle only on Incandescence. I've seen many planets in Transpace that lie about the Goldilocks zone.

Q2. So I was watching Mobile Suit Gundam: Iron Blooded Orphans. And suddenly, stations in Transcendence don't seem practical. For O2, we need Photosynthesis, and for that, we need starlight. Transpace stations look kinda closed up. Or have we discovered a catalyst or agent that can break CO2 into C and O2?

Q3. In MSG, they have those Ahab reactors to generate gravitational fields (I'm researching how). While in Trans, I've never read that anybody drifted around. Means I haven't read about microgravity in stations. So what do Transpace humans do for gravity (or gravitational field, if you like physics that much)?

We know from the Commonwealth slums that they use air scrubbers. These would presumably remove things like carbon dioxide and exhaust from the air.

Since stations presumably have their own reactors, it makes sense that they would use some of that energy to break down the carbon dioxide. This would be the same as on your ship, because the life support systems require constant power or you die.

Project Renegade (Beta) : "The Poor Man's Corporate Command!"
"Cowards die many times before their deaths; The valiant never taste of death but once. " -Julius Caesar as written by William Shakespeare, a notorious permadeath player.

Then why do us, the curren humans, not build specialized Solar Plants to break down CO2?

Because we don't have that much spare energy, and the problem becomes what to do with the CO2 you've scrubbed out of the atmosphere. With space stations you can handwave it a bit but it's still difficult (look at previous experiments on closed-systems like Biosphere 2 for how it can go wrong, especially if you rely on plants alone). With a planet...you need a way to store millions of tons of scrubbed CO2 in a convenient form.

Current carbon-capture tech for power plants (it does exist, it's just only being used in 1-2 places)tends to be tied to industrial processes that use it up later, so you don't have the problem of having to put it somewhere for the next few centuries. But to capture for capture's sake you need to store it so it won't just leak out again...pump it underground as a liquid or convert it to solid carbon (you could also dissolve it in water to make carbonic acid, but that's a pollutant in its own right and causes issues for shellfish and coral). And that's expensive and doesn't return a profit. You need the cost of removing carbon from the atmosphere to be low enough, and the price of carbon credits (or other incentives) to be high enough that it's economically viable. Right now it isn't, and the tech isn't up to it. Hopefully that changes.

On a spaceship or space station on the other hand, you have all the incentives you need (ie: Not dying) to make it work.

Then why do us, the curren humans, not build specialized Solar Plants to break down CO2?

Also, for the very simple reason that the most efficient and mutually beneficial way is to use plants and trees. (they are very efficient solar power plants )
If we only stop deforestation and allow for more plants and trees to exist, the rate of CO2 reduction will be much greater than all of the proposed methods that do not use plants combined.

Plants are really only a couple % efficient in practice, they are able to utilize only a fraction of the solar energy that falls on them

I was going to chime in and say this. Plants are about an order of magnitude worse at turning light into energy compared to modern photovoltaic cells. That said, I'm not familiar with how plants compare to artificial means when it comes to carbon capture and storage.

The efficiency in plants lies with the fact that they use sunlight to convert CO2. There is no other process on earth that is that efficient in converting CO2 with so little energy input. They use the carbon and other elements to grow themselves and release the oxygen they do not need.
It is for that reason that there are so many experiments with plants in space, they could solve most of the life support needs with very little energy use.

The efficiency in plants lies with the fact that they use sunlight to convert CO2. There is no other process on earth that is that efficient in converting CO2 with so little energy input. They use the carbon and other elements to grow themselves and release the oxygen they do not need.
It is for that reason that there are so many experiments with plants in space, they could solve most of the life support needs with very little energy use.

The problem with plants is that they cycle CO2. Only a small proportion is actually converted to stuff that hangs around, the rest gets put out again as CO2 later on. If you rely on plants, it tends to create large spikes in CO2 concentration....which has understandably bad results. Artificial air-scrubbing is a far better system for most purposes because you can control it more effectively. It's also more compact, and with a good power source (in RL, nuclear reactors are used on submarines) you can keep it up for a long time, given fairly cheap raw materials.

In short by themselves plants don't work for most small-scale closed systems (and 'anything people can build' counts as 'small' for these purposes). What plants do do for life support is add quality-of-life, as well as some emergency backup and luxury products.

The problem with plants is that they cycle CO2. Only a small proportion is actually converted to stuff that hangs around, the rest gets put out again as CO2 later on.

Mostly true for earth-like conditions with day and night cycles. When there is no light, plants also produce CO2, but given a constant light source, they don't do that. The net output of O2 for most plants is bigger than their CO2 output at night. This varies among plants, some have far higher O2 outputs, like Sansevieria's that always converts CO2 to O2 even at night, and also cleans other pollutants out of the air (they have been studied extensively by NASA for these reasons).